Not long ago I shared with you a power file from a ride and taught you how to do an analysis. You can read that post here. Being able to decipher a power file is an incredible way to learn about the effect of your profiles on your riders, as well as understand the cause and effect of cadence, resistance, and power on heart rate.

Don’t worry if you don’t have power, you will still learn! As I explained in that first post, whether you have a device to measure power or not, you are still producing power. This exercise will help you understand that wattage is the effort and heart rate is the response to that effort. With this knowledge, you’ll have more insight as you design your own profiles—power meters or not.

Please take a look at these files and take a stab at analysis. Or just ask me questions. You may want to teach this profile one of these days soon, so the more you understand how some riders might respond to it, the better. Take this opportunity to learn!

Here is how this will work. Please look at the two files and write in the comments what you think was taking place, or what caused the changes in power or heart rate. Then next week, I’ll repost these same files with an explanation and answer any questions.

These two files are from the same class, two different riders. Note that the class is actually 60 minutes long, but on the Stages bikes, the data isn’t recorded when it’s on “warm-up” mode. Neither of these riders recorded their warmup, so consider that it’s already been done.

As a reminder, in the files below, the yellow is cadence (RPM), visible on the right axis. The red is heart rate (BPM), also on the right axis. The pink is power (W, for watts) on the left axis. (Tip: Use a straight edge to line up with the corresponding axis to estimate the rpm, bpm, or wattage.)

Rider #1

This is basically how the ride should look, so you will compare rider #2 to this one. This rider’s FTP is 158.

There are 6 intervals. What is the intensity, cadence, and purpose?

The drops in power are essentially getting off the bike, so ignore these.

Rider #2

This rider’s FTP is about 118. She is 65 years old. It’s pretty obvious that she struggled a bit. Can you guess why?

These are *supposed* to be recovery!

What happened in this interval? (hint…look at the power as the cause)

What happened in this interval? (hint…look at the cadence as the cause)

Here are a few more questions to ask yourself:

Knowing that rider #2 struggled a bit, how might that impact your coaching in the future?

If you don’t have the ability to analyze your riders’ workouts like this, how might this knowledge help you when coaching your own riders through an interval class like this?

I’ll be back with the answers next week. Have fun!

4 Responses to “Analyze These Two Interval Profiles”

Karyn Silenzi’s response above is spot on.
I’ll add my inputs directly addressing a couple of questions that were posed, which focus on cause and effect:

2. What happened in this interval? (hint…look at the power as the cause)
Rider 2 went anaerobic to start this interval. Her power was over 125 watts, which exceeds her FTP. Her HR increased faster than the other intervals and she had to pull back. Since her cadence was on target, she must have had too much resistance or gear. As a result of going anaerobic, her power and cadence dropped below the target.
3. What happened in this interval? (hint…look at the cadence as the cause)
Her cadence was too high, likely causing a spike in HR. Her power looked OK, but the sudden increase in heart rate caused her to lower her power and cadence below target for the rest of the interval.

I think that a workshop on interpreting these charts or more articles like this will be beneficial to ICA members. It’s a value add that ICA can uniquely provide.

Ride plan is:
4′ fast feet, low/moderate gear.
4’intervals *6 with 2.5′ recovery in between.
Power for first interval is targeting 10% below FTP. Remainder of intervals at FTP.
Challenge is to keep RPM at 60 for first interval, 65 for second, 70 for third, 80 for fourth, 85 for fifth and 95 for final.
The real challenge here is to find the correct gear to maintain FTP at different speeds and different gears while maintaining consistency.
MHR of rider #1 is 165-170 bpm.
Recovery is less consistent after 3rd interval. RPMs at this point have dropped as is typical with these types of drills and effort level. Starting to see some cardiac drift.
On fourth interval rider #1 had trouble staying consistent (distracted perhaps?) and HR started to rise disproportionately. Perhaps gear choice was too heavy as W is quite high. This was corrected in subsequent intervals.
Big final push in last intervals with recovery immediately following.

Rider #2 – I only count 6 intervals so either first 4 min fast feet wasn’t done or they didn’t complete final interval of 6.
Gear starts off too heavy and recovery is non existent. Rider appears to start off intervals too fast and has hard time dialing in to RPM targets. Interval 2 is too fast and gear to heavy to hit target W. Should be at FTP. No recovery here either. Either speed/gear too high for proper rest period.
Interval 3 has too much gear and we start to see HR rise quickly.
Interval 4 there is too much gear so she needs to drop cadence and gear as she is burning through all of her glycolytic/ATP-CP stores.
Interval 5 looks good.
Interval 6 should have been at 95 but she went out too fast and couldn’t maintain speed and power.
In recovery HR drops only to 125 but her theoretical max is 155 so this would suggest she is potentially new to training, is stressed/dehydrated, is less fit, or is over training/under recovering. This is secondary however as many things can impact heart rate and recovery rates.

To coach this client I would have her do more cadence and gear drills. She needs to have faith that she can maintain FTP by slightly adjusting one or the other. It looks like she was just choosing the wrong combination and petering out. She was pushing too much gear often and that tactic blew up on her. Have faith that if you can hold a certain W for 20 minutes you can do so if broken up into 5 interval sets with PROPER RECOVERY.